Gas turbine engines are used as power plants in many industries, such as aviation, gas pipeline transmission, petroleum, steel, marine, and electric utilities. For many stationary and mobile applications, their characteristics have proved superior to those of competitive power plants. With ubiquitous use of gas turbine engines, even small increases in their efficiency and power output are highly desirable and needed. Accordingly, gas turbine engines have been combined with steam turbines in various ways in combined steam and gas plants.
To achieve increased efficiency, gas turbines engines have been used also in coal gasification plants, versions of which are basically comprised of an air separation unit and a coal gas production unit. In the air separation unit, an oxygen-enriched stream is produced. In the coal gas production unit, the oxygen-enriched stream is used to partially oxidize coal to generate a fuel gas. The fuel gas is used as fuel in a gas turbine engine. Even small further increases in efficiency and power output of such plants are highly desirable.